The spine and the hip are two anatomical districts that have close biomechanical relationship. The management of their degenerative disorders involves an in-depth biomechanical analysis of the patient, in order to define the proper hip-spine relation, using different biomechanical classifications that have been proposed in recent years. The changes in the spino-pelvic and acetabular parameters induced by prosthetic hip surgery and spinal surgery must be carefully evaluated, calculated and foreseen in the pre-operative phase, as they play a crucial role in defining the clinical success or failure of the operations. In this paper we present a case of a patient who underwent spinal surgery after a bilateral THA analyzing both spino-pelvic parameters and acetabular orientation and highlighting the strict relations between spine and hip.